Antiknock motor fuel



Patented Aug. 24, 1948 OFFICE ANTIKNOCK MOTOR FUEL Sol B. Wlczer, WashingtomD. C.

No Drawing. Application July'2l, 1943,

Serial No. 495,649

The present invention relates to anti-knock dope for addition to liquid motor fuels such as gasoline. and blends with other light combustibles.

It is known to add various mono lead alkyls and mixtures thereof to liquid motor fuels forOtto cycle internal combustion engines to prevent knocking. In a recent development it was found that such mixtures of lead alkyls where the alkyl is methyl and ethyl will give a range of boiling points to give more even distribution of lead com- Pounds over the boiling point range of the motor fuel, thus giving more even distribution of antiknock compound among the several cylinders of the engine with variable operating conditions, resulting in a higher road octane rating for the fuel doped therewith.

It is an object of the present invention to pro vide new anti-knock compounds of lead aikyls.

It is another object to provide new lead aikyls containing a higher proportion of lead in the compound.

It is a further object to provide a mixture of v lead aikyls of more widely variable volatility in mixtures of methyl and ethyl lead aikyls while maintaining the superior anti-knock doping effect thereof.

Another object is to provide a variation in boiling range of the various materials particularly the scavenger halogenated compounds commonly mixed with the lead alkyls so that they also may be evenly distributed by providing a mixture of Wide boiling point range.

In accordance with the present invention new lead alkyl compounds are provided wherein the lead concentration per molecule is increased. These new compounds may be removed. purified and used as anti-knock compounds per se, but inasmuch as their production is accomplished simultaneously with other lead aikyls as side reaction which improve their use as a mixture as well as the overall yield, the use of the resulting reaction products, a mixture is preferred.

The new compounds have the general formula:

(R)aPb-R'--Pb(R)3 where R is alkyl preferably methyl or ethyl and 2 Claims. (01. 44-69) chloride and heated for 3 hours at 80 R is alkylene, preferably ethylene or methylene.

2 and by variation of alkyls between methyl and ethyl many other homoiogues are possible.

The compounds are prepared in several ways substantially according to the standard methods of preparing lead aikyls with the modification that one molecule of alkylene dihalide is reacted in the presence of a catalyst with two molecules either of trialkyl lead or its equivalent. Such equivalent may be (1) two molecules of tetraalkyl lead, one molecule of hexa-alkyl di-lead, (2) capable of decomposing to two molecules of trialkyl lead, or (3) 6 molecules of alkyl halide and 2 molecules of lead in the form of an alloy with sodium (846% of sodium), likewise capable of forming two molecules of trialkyl lead. As stated above, the methyl and ethyl radicals are preferred as aikyls and methylene and ethylene radicals are preferredas the alkylene radicals. Chlorine and bromine are preferred as the halogen substituents. As to the catalyst, anhydrous aluminum chloride is preferred, but anhydrous ferric chloride, boron fluoride and active aluminum alloy. The last named catalyst is an active catalyst consisting of an alloy made from aluminum and small quantities of iron, copper, zinc and silicon.

Example I V 534 grams of lead tetramethyl is placed in an autoclave together with 660 grams of ethylene dibromide and 6 grams of anhydrous aluminum C. After this period methyl bromide is removed by distillation and the residue filtered and used as anti-knock dope in motor fuel. It will consist of a solution of ethylene di-(lead tri-methyl) (CHaMPbCHzPMCHah, ethylene (lead trimethyl) (lead di-methyl ethylene bromide) (CH3) aPbCHzCHaPb (CH3) 2CHzCH2Br products including some I Example II 323 grams of lead tetraethyl, 267 grams of lead tetramethyl are mixed with 300 grams of ethylene dibromide, 300 grams of methylene dibromide and grams of aluminum chloride and are heated 7 in an autoclave for 2 hours at 88 C. The alkyl (methyl) and (ethyl) bromides are removed by distillation and the complex mixture of lead alkyls and alkylene di-lead alkyls dissolved in alkylene dibromides are filtered and used as antiknock dope for gasoline. It is pointed out that the scavenger solvent in this case will not only produce a wider mixture of alkylene dilead alkyls, but as scavenger will be more evenly distributed thru variable engine operating conditions. If desired the reaction product may be distilled in a vacuum or steam distilled and selected fractions may be used as anti-knock. As before, the more volatile methyl and ethyl bromides need not be removed, or only partially removed as desired, or additional alkyl halides may be added as in the previous example.

Example III 474 grams of dilead hexamethyl are mixed with 154 grams methylene dibromide and 4 grams of anhydrous aluminum chloride, and the mixture is dissolved in 200 grams of dry hexane. The solution is heated for 2 hours at 100 C. and the methylene di- (lead tri-methyl) isolated by steam distillation and used as an anti-knock.

Example IV Example V 534 grams of lead tetramethyl, is mixed with 154 grams of methylene dibromide 400 grams of hexane and 4 grams of aluminum chloride and the mixture is heated for 4 hours at 80 C. in an autoclave. The lead compounds are separated by distillation or used directly as anti-knock dope.

Example VI 304 grams of ethyl chloride, 120 grams of methyl chloride, 100 grams of 1,2 ethylene dichloride 2700 grams of lead sodium alloy containing of sodium 5 grams of aluminum al- 10y containing 7% Cu, 1.5 zinc and 1% Fe are heated in an autoclave at 85 C. 2% hours. The free alkyl halides are removed by distillation and the residue is vacuum distilled, to separate individual or mixtures of lead alkyls and ethylene di-lead alkyls.

Example VII of active aluminum alloy as described in Example -6 and heated at C. for 4 hours in an auto clave. At the end of this period, the ethyl chloride and methylene dichloride are separated from the lead compounds by distillation or if desired the lead compounds may be used directly as antiknick dope without purification other than filtration In actual use these compounds have superior road anti-knock value.

Moreover as pointed .out by properly proportioning the scavenging agents over a wide boiling range the cylinders of the engine will remain cleaner.

It will be obvious that the dope may be added to various motor fuels such as, liquid hydrocarbon and blends thereof, with other combus-- tibles for anti-knock doping thereof in various proportions.

Moreover the anti-knock hereof may be blended with other known doping agents to improve the effect thereof such as compounds which improve the susceptibility of the motor fuel to having its anti-knock improved by lead alkyls, stabilizers which prevent decomposition of leaded gasolines in storage by oxidation, top cylinder lubricants, and dyes, etc.

I claim:

1. A gasoline containing, in small but sufiicient quantity to improve the anti-knock quality thereof, a compound of the formula (R) aPbR'Pb(R) V wherein R is an alkyl radical selected from the group consisting of methyl and ethyl and R is an alkylene radical selected from the group consisting of methylene and ethylene.

2. A gasoline containing, in small but sufficient quantity to improve the anti-knock quality thereof, a compound of the formula (cmiarbcmrmcmn son B. WICZER.

REFERENCES CITED The following references are of recordin the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Griittner et al., Berichte der Deutschen Chemischen Gesellshaft, vol. 50, page 1557.

Emschurller, Comptes Residues, vol. 183 (1926),

' pages 665 667. 

